1. Field of the Invention
This invention relates to heat dissipation and, more particularly, to a vapor chamber effectively saving a cost of thermal interface materials and a base of the vapor chamber and a method for manufacturing the same.
2. Description of the Related Art
In recent years, heat dissipation of the electronic device is gradually interested as an electronic device is gradually developed to be light, slim, short, and small. Particularly, present consuming electronic products, such as a digital camera, a cell phone, a notebook computer and so on, have more complicated functions and include more and more power transistor elements. Therefore, an inner space of a casing becomes smaller, and fans are limited in order to reduce noise so that thermal management of the electronic devices becomes more and more serious and needs to be solved.
A casing of the electronic device is mostly made of aluminum-magnesium alloy in order to allow the power transistor elements of the electronic device to run at a normal operating temperature to maintain a normal lifespan thereof. Further, heat generated by the power transistor elements of the electronic device is transferred to the metal casing via a thermal interface material (TIM), such as a thermal grease and thermal pad, and a thermal conducting element, such as a heat pipe, a vapor chamber, a loop heat pipe and so on. The temperature of the power transistor elements can be effectively reduced to dissipate the heat because the metal casing has a great heat dissipating area.
In most heat dissipating devices, a vapor chamber (also called flat plate heat pipe) has excellent transverse and longitudinal thermal conduction characteristics. Therefore, the vapor chamber is widely used as a heat dissipating device of an electronic device, such as a central processing unit, a graphic processing unit, a high power transistor, a high power light-emitting diode and so on, thereby ensuring that the electronic device can work in a normal state and can avoid a breakdown caused by overheating.
FIG. 1A and FIG. 1B are a top view and a sectional view showing a power transistor element of an electronic device attached to a metal casing via a vapor chamber in the prior art, respectively. In FIG. 1A and FIG. 1B, heat generated by a power transistor element 10 of an electronic device 1 is transferred to an upper cover 121 (a heating side) of a vapor chamber 12 via a TIM t1.
Then, the vapor chamber 12 greatly transfers the heat to a bottom plate 122 (a cooling side) of the vapor chamber 12 via a phase change of a working fluid in the vapor chamber 12 between liquid phase and gas phase. The bottom plate 122 of the vapor chamber 12 then transfers the heat to a metal casing 14 of the electronic device 1 via a TIM t2. Thereby, the heat can be dissipated through a greater heat dissipating area of the metal casing 14, thus to reduce a common partial high-temperature condition in the electronic device 1. However, the heat dissipating mode in the conventional electronic device 1 still has a great of disadvantages.
For example, the heat generated by the power transistor element 10 of the electronic device 1 needs to be transferred to the vapor chamber 12 via the TIM t1, and the vapor chamber 12 also needs the TIM t2 to transfer the heat to the metal casing 14. Thermal resistance is greater since thermal conductivity of the TIM t1 and t2 is lower. In addition, since a contact surface between the power transistor element 10 and the TIM t1, between the TIM t1 and the vapor chamber 12, between the vapor chamber 12 and the TIM t2, or between the TIM t2 and the metal casing 14, is not flat or smooth, greater contact thermal resistance may be generated so that the effective thermal conductivity of the electronic device 1 is worse. Therefore, the heat generated by the power transistor element 10 of the electronic device 1 fails to be effectively dissipated, and the operating temperature thereof is still higher, which greatly reduces reliability and the lifespan of the electronic device 1.